Self sealing cap construction



Aug- 1965 R. ,L. PLUNKETT 3,203,571

SELF SEALING CAP CONSTRUCTION 7 Filed Dec. 6, l960 3 Sheets-Sheet 1 INVENTOR Aug. 31, 1965 R. 1.. PLUNKETT' 3,203,571

SELF SEALING CAP CONSTRUCTION Filed Dec. 6, 1960 3 SheetS -Sheet 2 A 66 2 6/ G I a I 62 6.5 50

Y 3 162 79 2:2 ZP-76.

INVENTOR Kobenf L. Plan fieZZ ATTORNEYS,

United States Patent SELF SEALING CAP CONSTRUCTION Robert L. Plunkett, 14 Orsini Place, Larchmont, N.Y. Filed Dec. 6, 1960, Ser. No. 74,087 12 Claims. (Cl. 21540) in which the screwing down of the screw cap will give an automatic sealing effect.

It is among the objects of the present invention to provide a plastic cap construction, and particularly a pliable cap construction which will have sufficient resiliency to a form a firm, solid, rigid cap, but which at the same time will have a sutlicient pliability so that without a separate gasket portions of the cap may be utilized to give a seal.

Another object is to providea plastic screw cap for.

glass jars, tumblers and other containers which will permit ready sealing of a vessel or enclosure and particularly a bottle or tumbler, so as to prevent escape of liquid or other enclosed product from the inside, and also prevent the entry of air which may be contaminated, dirt or other bacteria laden substances from the outside.

Still another object is to provide a gasketless screw cap which will, without undue twisting pressure or use of tools, enable a satisfactory seal to be achieved without great force being applied to the screwing on of the cap, while at the same time the seal may be readily released.

Another object is to provide a screw cap which is formed of a plastic or similar material which is of inverted cup shape with a base and :1 depending cylindrical skirt or sidewall, and which has an integral, downwardly extending internal seal forming flange adjacent the junction of the base and sidewall, which sealing flange is located so that it will wrap around the top edge at the mouth of the bottle or other container on which the cap is used, thereby effecting engagement with a side and end edge of the container wall and providing a more effective seal.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only and not by way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

Although not limited thereto, the present invention will be particularly described in connection with synthetic plastic materials of the type of polyethylene which, although sul'ficiently rigid to form a readily applied cap, nevertheless may have integral channels or ridges which are sufficiently pliable to give a sealing etfect without liner or gasket.

In achieving the preferred construction, the device is made in the form of an inverted cup with the usual base and cylindrical sidewall and with an interior thread on the sidewall to engage and tighten upon the top of the tumbler or jar. At the same time, there is provided on the interior base, preferably adjacent the cylindrical sidewall, one or more ridges or projections of such a nature that they may be compressed as the cap is tightened into position to give a gasket or liner effect and also, if necessary, a compressed air or air pocket etfect.

These internal. ridges constitute sealing flanges which may extend outwardly from and be formed of the same material as the cylindrical wall or the base of the cap construction.

With the foregoing and other objects in view the in- 3,203,571 Patented Aug. 31, 1965 vention consists of the novel construction, combination and arrangement of parts as hereinafter more specifically described, and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the claims hereunto appended.

In the drawings wherein like reference characters denote corresponding parts throughout the several views:

FIG. 1 is a transverse sectional view of a cap which is formed of a stiff or rigid polyethylene according to the present invention, showing the cap before application to a jar or tumbler; I

FIG.. 2 is a trasverse sectional view of the cap of FIG. 1 as applied to a tumbler and tightened down to form a seal;

FIG. 3 is a transverse sectional view of another embodiment of a polyethylene cap according to the present invention;

FIG. 4 is a transverse sectional view of the cap of FIG.

3 as applied to a jar or tumbler and tightened down to position;

FIG. 5 is a transverse sectional view of a further embodiment of the cap;

FIG. 6 is a transverse vertical sectional view similar to FIG. 5 with the cap tightened down in position upon the top of a jar or tumbler;

FIG. 7 is a transverse sectional view of a further form of the cap;

FIG. 8 is a transverse sectional view of the cap of FIG. 7 tightened down into sealing position on a jar or tumbler;

FIG. 9 is a transverse sectional view of still another form of sealing cap screws into position on a jar or tumbler;

FIG. 10 is a transverse sectional view of a yet further form of cap which comprises a rigid polyethylene insert in a metal shell, which insert is without a cylindrical skirt;

FIG. 11 is a transverse sectional view of a still further form of the cap;

FIG. 12 is a transverse sectional view of the cap of FIG. 11 applied to the screw threaded top of a container and tightened down into seal forming relation thereon;

FIG. 13 is a transverse sectional view of still another form of the cap;

FIG. 14 is a transverse sectional view of the cap of FIG. 13 applied to the screw threaded top of. a container and tightened down into seal forming relation thereon;

FIG. 15 is a transverse sectional view of yet another form of the cap;

FIG. 16 is a transverse-sectional view of the cap of FIG. 15 applied to the screw threaded top of a container and tightened down into seal forming relation thereon; and

FIG. 17 is a partial transverse sectional view, to an enlarged scale, illustrating a further modification of the cap.

Referring to FIG. 1 there is shown with a base 10 and a skirt 11.

The skirt 11 is interiorly provided with a screw thread 12 to fit upon the thread tumbler B.

Extending inwardly from the junction of the cap and skirt, as indicated at 14, there is an inwardly and downwardly projecting flange 15 formed integrally with the base and-skirt 10 which has a downwardly extending ridged portion 16 which, as indicated in FIG. 2, is designed to fit inside of the internal face 17 of the jar or tumbler B.

It will be noted that the cap A is of maximum thickness at its middle portion 18 and becomes of decreased thickness at its intermediate portion 19 and then decreases to minimum thickness at 20 adjacent the skirt where flexibility ,is most desired.

a typical cap A 13 at the top of the jar or The intermediate portion 19 will leave the shoulder 11 which forms a sealing edge with the outer face 22 if the flange member 15.

It will be noted that when the cap A is screwed down IS shown in FIG. 2, an air cushion pocket 23 will be Formed at the thinnest portion 20 and above the face 22 )f the flange 15 outside of its seal with the shoulder 21.

This will give thorough sealing and the compressed III cushion 23 will permit ready release of the cap with- )ut requiring the application of substantial rotary force )1 turning clamps.

In the form of FIGS. 3 and 4 the cap C will have a :ylindrical side flange and a base 31 of maximum hickncss at 32 with the shoulders 33 and 34.

The interior of the cylindrical flange 30 will have a crew thread 35 to engage the screw thread 36 on the ar and it will also have the downwardly obliquely proccting scaling flange 37.

When the cap C is screwed down on the jar D the to :dge 38 will compress the flange 37 so that it will tightly :ontact the shoulder 33 and seal the jar D with a comircssed air cushion 39.

In the embodiment of FIGS. 5 and 6 the cap E is pro- Iidcd with a skirt and the base 46 which has a rela ively wide uniform thick portion 47 and a peripheral ecess 48.

The obliquely depending flange 49 has a curved or a :ircular outer edge 50 which circular outer edge fits tgainst and contacts the slanting or oblique face 51 as ndicated at 52 in FIG. 6.

This is accomplished when the screw thread 53 on the rap E is engaged with the screw thread 54 on the jar F md the cap is tightened or screwed clown on the jar so is to compress the flange 49 as indicated. This compresion will form a pocket 55.

In the embodiment of FIGS. 7 and 8 the cap G has a kirt and a base 61 with an internal thread 62.

The periphery of the interior of the base has a recess 33 with the flanges 64 and 65 extending entirely around he interior of the base 61 adjacent the junction of the kirt and base at 66.

When the cap G is screwed down on the jar H two langcs 64 and 65 are compressed upwardly as indicated n FIG. 8 by the top edge 67 of the jar H, they will :omprcss an air pocket at 68 and seal the top space of he jar. This connection is formed by screwing together he jar thread 69 and the interior cap thread 62.

In the embodiment of FIG. 9 the cap I has a base ind a skirt 76 with an internal thread 77 engaging the bread 78 of the jar K.

The interior inside face 79 of the cap I has the ridges it) which are formed by cutting a groove at 81 into a irojecting peripheral portion or ridge 82 around the nternal periphery of the cap adjacent the junction at 83 If the base 75 and skirt 76.

When the cap I is tightened down on the jar K the idges engage the upper top edge 84 of the jar K and orm a tight seal.

In the embodiment of FIG 10 the polyethylene memier L is an insert inside of the metal cap shell M. The netal cap M has a side skirt with a lower inturned :dge 91 which forms a screw thread connection and a I856 92.

Abutting against the base 92 and adhesively or othervise mounted thereon is the insert L having the thickest iortion 93 at the center thereof with peripheral shoullers 94 and 95 and an oblique downwardly and inwardly xtending flange 96. This flange 96 will function as is tlready indicated in connection with FIGS. 1 to 6 when he top of a jar is tightened thereinto.

In the embodiment illustrated in FIGS. 11 and 12, he cap N is formed with a base 100 and a depending IUl'lPlICl'fll skirt 101, the latter having an internal thread 02. A continuous scaling flange or fin 103 extends invardly around the internal periphery of the base 100, at

4 the junction of the base 100 and the skirt 101. The

flange 103, in its non-sealing position, is inclined down-.

wardly and forms with the interior wall of the base 100 an inwardly opening recess 104 of generally V-shaped cross section. A small peripheral bead 105 of generally semi-circular cross section is formed on the interior wall of the base 100 opposite the inner margin of the sealing flange 103 for cooperation with the sealing flange 103 when the latter is in seal forming position. The sealing flange 103, preferably, is formed so that it has a somewhat thicker section at its outer margin where it joins the body of the cap and tapers to a thinner section at its inner margin. It extends inwardly a suflicient distance so that when the cap N is placed on the top of the jar O and the internal thread 102 of the c ap is engaged with the cooperating external thread 106 on the jar top and the cap is tightened down, the sealing flange 103 will wrap around the top edge 107 of the jar with the area of engagement extending an appreciable distance around the outside periphery of the jar edge, as indicated at 108 in FIG. 12, as well as across the top edge 107. The innermost margin of the sealing flange 103 engages with the bead 105 which assists in forcing the flange into tight engagement with the innermost portion of the top edge 107 which may be somewhat rounded as illustrated. Thus the flange or fin 103 when clamped between the upper edge 107 of the jar mouth and the oppositely disposed interior of the cap base 100 contacts a relatively wide surface area extending around the periphery of the former and insures a tight and effective seal.

The inward or upward hinging of the sealing'flange 103 when contacted and forced into seal forming engagement with the base 100 of the cap and the top edge 107 of the jar traps air in the pocket 109 which is formed at the outermost portion or base of the recess 104, providing an air cushion which functions as in the previously described embodiments of the cap.

In the embodiment illustrated in FIGS. 13 and 14, the cap P is formed with a base 110 and a depending peripheral skirt 111, the latter having an internal thread 112. A continuous sealing flange or fin 113 extends inwardly around the internal margin of the base 110, adjacent the junction of the base 110 and the skirt 111, The flange 113, in its non-sealing position, is inclined downwardly and forms with the adjoining portions of the interior wall of the base 110 an inwardly opening recess 114 of generally V-shaped cross section. A small peripheral bead 115 of generally semi-circular cross section is formed on the interior wall of the base 110 which is spaced inwardly of the margin thereof and which is opposite the inner margin of the sealing flange 113 for cooperation with the sealing flange 113 when the latter is in seal forming position. The sealing flange 113, preferably, is formed so that it has a somewhat thicker section at its outer margin where it joins the base 110 of the cap and tapers to a thinner section at its inner margin. It extends inwardly a sufflcient distance so that when the cap P is placed on the top of the jar Q and the internal thread 112 of the cap is engaged with the cooperating external thread 116 on the jar and the cap is tightened down the sealing flange 113 will wrap around the top edge 117 of the jar mouth with the area of engagement extending an appreciable distance around the outside periphery of the jar edge, as indicated at 108 in FIGURE 14, as well as across the top edge 117. The innermost margin of the sealing flange 113 engages with the bead 115 which assists in forcing the flange or fin 113 into tight engage ment with the innermost portion of the top edge 117 which may be somewhat rounded as illustrated. Thus the flange 113 when clamped between the upper edge 117 of the jar mouth and the oppositely disposed interior of the cap base 110 contacts a relatively wide surface area extending around the periphery of the former and insures a tight and effective seal.

The inward or upward hinging of the sealing flange 113 when contacted and forced into seal forming engagement with the base 110 of the cap and the top edge 117 of the jar traps air in the pocket 119 which is formed at the outermost portion or base of the recess 114, providing -an air cushion which functions as in the previously described embodiments of the cap.

In the embodiment illustrated in FIGS. 15 and 16, the cap R is formed with a base or top panel portion 120 and a depending peripheral skirt 121, which skirt has an internal thread 122. A continuous sealing flange or fin 123 extends inwardly around the internal margin of the base 120 which flange is spaced inwardly a small distance from the junction of the base 120 and the skirt 121. The flange 123, in its non-sealing position, is inclined downwardly and forms with the interior wall of the base 120 an inwardly opening recess 124 of generally V-shaped cross section. A small peripheral bead 125 of generally semi-circular cross section is formed on the interior wall of the base 120 opposite the inner margin of the sealing flange 123 for cooperation with the sealing flange 123 when the latter is in seal forming position. The sealing flange 123, preferably, is formed so that it has a somewhat thicker section at its outer margin where it joins the base 120 of the cap and tapers to a thinner section at its inner margin. It extends inwardly a sufficient distance so that when the cap N is placed on the top of the jar S and the internal thread 122 of the cap is engaged with the cooperating external thread 126 on the jar top and the cap is tightened down the sealing flange 123 will wrap around the top edge 127 of the jar with the area of engagement extending an appreciable distance around the outside periphery of the jar edge, as indicated at 128 in FIG. 16, as well as across the top edge 107. The innermost margin of the sealing flange 123 engages with the bead 125 which assists in forcing the flange into tight engagement with the innermost portion of the top edge 127 which may be somewhat rounded as illustrated. Thus the flange or fin 12 3 when clamped between the upper edge 127 of the jar mouth and the opposite disposed interior of the cap base 12% contacts a relatively wide surface area extending around the periphery of the former and insures a tight and effective seal,

The inward or upward hinging of the sealing flange 123 when contacted and forced into seal forming engagement with the base 129 of the cap and the top edge 127 of the jar trapsair in the pocket 129 which is formed at the outermost portion or base of the recess 12 4, providing an air cushion which functions as in the proviously described embodiments of the cap.

In FIG. 17, there is illustrated a modification of the cap whichmay be embodied in any of the previously described forms thereof. The illustrated cap T has a top panel 130 and :1 depending peripheral skirt 131. The base or top panel 130 has a projecting annular bead 135 on its inner surface and a continuous seal forming fin or flange 133 which extends inwardly around the internal margin of the base 130 and which is clamped in wrapped around engagement with the top edge of the mouth of the jar U as shown, when the cap T is secured over the mouth of the jar U, so as to form an air pocket 139 between the sealing flange 133 and the interior Wall of the base 130. The air pocket 139 thus formed is provided with a bleed opening 140 in the form of a small passageway to the exterior of the cap so that when the cap is sealed any gas or pressure, in excess of a predetermined amount, will force the top panel 130 upwardly and pass between the upper surface of the sealing flange 133 and the inside of the top panel, escaping through the vent hole 140 in the top panel 130. The outside top edge sea] at 138 is not disturbed by the venting action so that the seal is not broken.

It is apparent that by utilizing a stiff or rigid polyethylene as described, there is provided a simple, readily applied and removable cap without the need of using a separate liner and without a gasket, the cap being molded in one piece with the seal form-ing flanges or fins formed simultaneously with the top panel or base during the molding operation.

The thickness of the polyethylene in the skirt and base is sutficiently rigid whereas the projecting sealing flange or flanges are sufficiently thin to provide the flexibility required to form a perfect seal.

The sealing flange may project obliquely downwardly at angles varying from 45 to 60 and if desired, the top of the jar may be turned or shaped so as to cooperate in compressing the flange.

The forms of the cap which are illustrated may be molded on a die or' core and removed from the forming or molding die by unscrewing the same when the cap is provided with an internal thread on the skirt which terminates at the top or base panel of the cap. When it is desired to mold the cap with the thread terminating short of the top or base panel, so as to avoid sharp angles at the juncture of the skirt and base panel, the die or core is modified accordingly and the cap, when finished, is removed or stripped from the die by a stripper plate or ring which engages the bottom edge of the skirt and forces the cap off the end of the die.

While there has herein been illustrated and described the preferred embodiments of the invention, it is to be understood that applicant does not limit himself to the precise construction herein disclosed, and the 'right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

I claim:

1. An all-plastic molded cap comprising a body having a top panel portion and a depending skirt portion,

retaining means on the interior of said skirt portion for engaging retaining means on a container so as to releasably secure said cap in sealing relationship thereon, a flexible annular sealing fin being elongated in radial cross-section projecting downwardly and inwardly into the interior of said cap from its integral circumferential connection to the cap body adjacent the juncture of said top panel and depending skirt portion, and circumferential shoulder means having a bottom annular sealing surface on the underside of said top panel portion and defining the inner sidewall of an upwardly extending annular recess lying above said sealing fin, said annular sealing surface being sealingly engaged by the free inner end of said sealing fin when said cap. is secured in sealing engagement on a container whereby the underside of said sealing fin forms a seal with the rim of said container and said sealing flange forms the flexible bottom wall of a sealed air pocket lying above said rim and formed by sealing of said annular recess.

2. An all-plastic molded cap comprising a body having a top panel portion and a depending skirt portion,

retaining means on the interior, of said skirt portion for engaging retaining means on a container so as to releasabl'y secure said cap in sealing relationship thereon, a flexible annular sealing fin being elongated in radial cross-section projecting downwardly and inwardly into the interior of said cap from its integral circumferential connection to the cap body adjacent the juncture of said top panel and depending skirt portions, and circumferential shoulder means having a bottom surface on the underside of said top panel portion and defining the inner sidewall of an upwardly extending annular recess lying above said sealing fin, said surface being engaged by the free inner end of said sealing fin when said cap is secured in sealing engagement on a container whereby the underside of said sealing fin forms a seal with the rim of said container and said sealing flange forms the flexible bottom wall of an air pocket lying above said rim and formed by said annular recess.

3. An all-plastic self-sealing closure cap comprising retaining means on the interior for engaging retaining means on a jar so as to rclcasably secure said cap in scaling relationship thereon, a thin flexible integrally molded oblique flange extending inwardly and downwardly from the interior corner at the junction of said skirt and base, said oblique flange having a circumferential ridge at the outer lower face thereof to fit into the neck of said jar when said cap is retained in sealing relationship thereon.

4. An all-plastic molded cap comprising a body having a top panel portion and a depending skirt portion, retaining means on the interior of said skirt portion for engaging retaining means on a container so as to releasably secure said cap in sealing relationship on the mouth of said container, a flexible annular sealing flange of substantial radial extent. projecting downwardly and inwardly into the interior of said cap from an integral circumferential connection with said top panel portion adjacent the juncture of said top panel and depending skirt portions, a circumferential bead on the under side of said top panel portion, said head being engaged by the free inner margin of said sealing flange when said cap is secured in sealing engagement on said container, said sealing flange having a section at its base where it is joined to said top panel which is thicker than at the free margin thereof whereby when said cap is tightened down on said container said sealing flange is wrapped around the rim of the container and the bottom surface thereof forms a seal with said rim which extends across the top edge and about the outside peripheral edge of said rim.

5. An all-plastic molded cap comprising a body having a top panel portion and 21 depending skirt portion, retaining means on the interior of said skirt portion for engaging retaining means on a container so as to releasably secure said cap in sealing relationship on the mouth of said container, a flexible annular sealing fin extending downwardly and inwardly into the interior of said cap from an integral circumferential connection with said top panel portion adjacent the juncture of said top panel and depending skirt portions, the upper surface of said fin defining the bottom of an annular recess which opens inwardly and downwardly of the margin of said' top panel portion in the non-seal forming position of said sealing fin, a circumferential bead on the underside of said top panel portion in opposed relation to the free inner margin of said sealing fin, said bead being engaged by the free inner margin of said sealing fin when said cap is secured in sealing engagement on said container, said sealing flange having a thickened radial section at its base where it is joined to said top panel whereby when said cap is tightened down on said container said sealing flange is wrapped around the rim of the container and the bottom surface thereof forms a seal with said rim which extends across the top edge and about the outside peripheral edge of the rim of said container while the open inner side of said annular recess is closed and an air filled pocket is formed above said sealing fin.

6. An all-plastic self-sealing closure cap comprising a circular base and 21 depending circular skirt having retaining means on the interior for engaging cooperating retaining means on the neck of a receptacle so as to releasably secure said cap in sealing relation over the mouth of said receptacle, and a relatively thin flexible integrally molded sealing flange extending inwardly and downwardly from the interior corner of said cap at the junction of said base and skirt, said flange forming with adjoining portions of said base an inwardly opening annular recess of generally V-shape in radial section when said flange is in non-sealing position with the maximum diameter of said recess being greater than the outside diameter of the mouth of said receptacle whereby said flange is wrapped around the top and outside edge of the rim forming the mouth of said receptacle when said cap is secured thereon.

7. An all-plastic molded cap comprising a body having a base and a depending peripheral skirt, retaining means on the interior of said skirt for engaging retaining means on the neck of a receptacle so as to releasably secure said cap in mouth sealing relation thereon, a flexible annular sealing flange extending downwardly and inwardly into the interior of said cap from an integral circumferential connection with said base adjacent the juncture of said base and depending skirt, a circumferential bead on the under side of said base, said bead being engaged by the free inner margin of said sealing flange when said cap is secured in sealing engagement on a container, said sealing flange having a radial cross section which is relatively thin at its inner end and tapers to substantial thickness at its outer end where said flange is joined to said base whereby said sealing flange is wrapped around the rim at the mouth of the receptacle when secured thereon and the bottom surface extends across the top edge and about the outside peripheral edge of the rim of said receptacle so as to form a seal of substantial width.

8. An all-plastic molded cap comprising a circular body having a top panel portion and a depending peripheral skirt portion, retaining means on the interior of said skirt portion for engaging retaining means on the mouth forming neck of a container so as to releasably secure said cap in sealing relationship with the rim thereof, a flexible annular sealing flange extending downwardly and inwardly into the interior of said cap and having an integral cireumferential connection with said top panel portion adjacent the juncture of said top panel and depending skirt portions, said connection being in the area between the outside edge of the rim and the inside surface of said skirt portion, a circumferential projecting rib on the under side of said top panel portion, said rib being positioned inwardly of the outer edge of said top panel portion where it is engaged by the free inner margin of said sealing flange when said cap is secured in sealing engagement on said container, said sealing flange having a portion at its base where it is joined to said top panel which extends below the top face of said rim whereby said sealing flange is wrapped around the top face and the outside edge of the rim of the container when in seal forming relation and the bottom surface thereof forms a seal with said rim which extends across the top face and about the outside peripheral edge thereof.

9. An all-plastic molded cap comprising a body having a top panel portion and a depending skirt portion, retaining means on the interior of said skirt portion for engaging retaining means on a container so as to releasably sepure said cap in sealing relationship on the mouth of said container, a flexible annular sealing fin extending downwardly and inwardly into the interior of said cap from an integral circumferential connection with said top panel portion adjacent the junction of said top panel and depending skirt portions, the upper surface of said fin defining the bottom of an annular recess which opens inwardly and downwardly of the margin of said top panel portion in the non-seal forming position of said sealing fin, said sealing fin having a thickened radial section at its base where it is joined to said top panel whereby when said cap is tightened down on said container said sealing fin is wrapped around the rim of the container and the bottom surface thereof forms a seal with said rim which extends across the top edge and about the outside peripheral edge of the rim of said container while the open inner side of said annular recess is closed and an air pocket is formed above said sealing fin, and said top panel portion having an air passageway extending from said air pocket to the outside of said cap.

10. An all-plastic molded cap as defined in claim 1 and said top panel portion having an air vent hole connecting said air pocket with the outside of said cap.

11. An all-plastic molded cap comprising a body having a base and a depending peripheral skirt, retaining means on the interior of said skirt for engaging retaining means on the neck of a receptacle so as to releasably secure said cap in mouth sealing relation thereon, a flexible annular scaling flange extending downwardly and inwardly into the interior of said cap from an integral circumferential connection with said base adjacent the juncture of said base and depending skirt, a circumferential abutment on the under side of said base, said abutment being engaged by the tree inner margin of said sealing flange when said cap is secured in sealing engagement on a container, said sealing; flange having a radial cross. section which is relatively thin at its inner end and tapers to substantial thickness at its outer end where said flange is joined to said base whereby said sealing flange is wrapped around the-rim at the mouth of the receptacle when secured thereon and the bottom surface extends across the top edge and about the outside peripheral edge of the rim of said receptacle so as to form a seal of substantial width.

12. An all-plastic molded cap comprising a body having a top panel portion and :1 depending skirt portion, retaining means on the interior of said skirt portion for engaging retaining means on a container so as to releasably secure said cap in sealing relationship thereon, a flexible annular sealing fin being elongated in radial crosssection projecting downwardly and inwardly into the interior of said cap from its integral circumferential connection to the cap body adjacent the juncture of said to panel and depending skirt portion, and an annular abut ment on the underside of said top panel portion and de fining the inner sidewall of an upwardly extending an nular recess lying above said sealing fin, said annula: abutment being sealingly engaged by the free inner ent of said sealing fin when said cap is secured in sealin engagement on a container whereby the underside of sait sealing fin forms a seal with the rim of said containei and said sealing fin forms the flexible bottom wall of z ,sealed air pocket lying above said rim and formed by sealing of said annular recess.

References Cited by the Examiner UNITED STATES PATENTS 2,528,506 11/50 Foye 18 5S 2,700,186 '1/55 Stover 18-5S 2,980,275 4/61 Lundgren 215-63 3,002,642 10/61 Watson 215--63 GEORGE O. RALSTON, Primary Examiner.

EARLE J. DRUMMOND, JOSEPH R. LE CLAIR,

" Examiners. 

1. AN ALL-PLASTIC MOLDED CAP COMPRISING A BODY HAVING A TOP PANEL PORTION AND A DEPENDING SKIRT PORTION, RETAINING MEANS ON THE INTERIOR OF SAID SKIRT PORTION FOR ENGAGING RETAINING MEANS ON A CONTAINER SO AS TO RELEASABLY SECURE SAID CAP IN SEALING RELATIONSHIP THEREON, A FLEXIBLE ANNUAL SEALING FIN BEING ELONGATED IN RADIAL CROSS-SECTION PROJECTING DOWNWARDLY AND INWARDLY INTO THE INTERIOR OF SAID CAP FROM ITS INTERGRAL CIRCUMFERENTIAL CONNECTION TO THE CAP BODY ADJACENT THE JUNCTURE OF SAID TOP PANEL AND DEPENDING SKIRT PORTION, AND CIRCUMFERENTIAL SHOULDER MEANS HAVING A BOTTOM ANNULAR SEALING SURFACE ON THE UNDERSIDE OF SAID TOP PANEL PORTION AND DEFINDING THE INNER SIDEWALL OF AN UPWARDLY EXTENDING ANNULAR RECESS LYING ABOVE SAID SEALING FIN, SAID ANNULAR SEALING SURFACE BEING SEALINGLY ENGAGED BY THE FREE INNER END OF SAID SEALING FIN WHEN SAID CAP IS SECURED IN SEALING ENGAGEMENT ON A CONTAINER WHEREBY THE UNDERSIDE OF SAID SEALING FIN FORMS A SEAL WITH THE RIM OF SAID CONTAINER AND SAID SEALING FLANGE FORMS THE FLEXIBLE BOTTOM WALL OF A SEALED AIR POCKET LYING ABOVE SAID RIM AND FORMED BY SEALING OF SAID ANNULAR RECESS. 